Service, get & extend in javascript and how are they being used

I am trying to make sense of some code snippets in javascript. But getting way too confused, it seems to be using all the symbols in all possible ways.

import Ember from 'ember';

export default Ember.Route.extend({
  metrics: inject.service(),

  activate() {
    this._trackPage();
  },

  _trackPage() {
    run.scheduleOnce('afterRender', this, () => {
      const page = document.location.href;
      const title = this.routeName;

      get(this, 'metrics').trackPage({ page, title });
    });
  }
});

q1: What are the keyword service, get, extend? What are they doing here? q2: Why is activate defining _trackPage separately? Why not put the reschedule code in activate() itself?